Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries full responsibility for disclosing behavior. It only states 'HEAD a public URL and return status only,' but does not explain what happens when other parameters are provided, whether parameters are mutually exclusive, or what 'status' means. The schema hints at many discarded values, but the description omits this entirely.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single sentence, which is concise, but it is too underspecified to be considered well-structured. It lacks any context about the tool's polymorphic behavior and does not front-load key constraints. It is not 'appropriately sized' for a 9-parameter tool.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with 9 optional parameters, no output schema, and no annotations, the description is grossly incomplete. It does not explain how parameters map to different operations, what the expected output format is, or how to distinguish this from similar sibling tools. An agent cannot reliably determine how to invoke it correctly beyond the single URL case.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, with each parameter having a meaningful description (e.g., 'discarded after the shape check'). The tool description adds no additional parameter semantics. The schema itself adequately documents individual parameters, so a baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies a specific action (HEAD a public URL) and a specific outcome (return status only). However, the input schema contains 9 unrelated parameters (city, zone, json, etc.) that the description does not mention, so it fails to convey the tool's full scope and could mislead an agent into thinking it only handles URL status checks.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description offers no guidance on when to use this tool versus its many siblings (e.g., normalize-url, validate-json, timezone). It does not specify conditions for selection or exclusions, leaving the agent to infer usage from the parameter names.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.